This invention relates to a snowmobile suspension unit and more particularly to an improved suspension unit for the forward portion of the drive belt of a snowmobile.
As is well known, snowmobiles travel over a wide range of territories and it is not uncommon for them to encounter unexpected and abrupt changes in terrain. In order to permit good control and yet a relatively soft ride when travelling over relatively smooth surfaces, it is particularly desirable to provide a suspension system that affords a fairly large degree of suspension travel. However, due to the construction and general configuration of a snowmobile, this is not always possible. Because of the relatively large space taken up by the drive belt, it has been difficult to provide a suspension system that will afford such wide degrees of suspension travel with full control throughout the entire range of travel. Although it has been proposed to mount the suspension medium externally of the drive belt, such an arrangement not only unduly widens the body of the snowmobile but further places the suspension components in a location where they may be damaged. In addition, such outboard mounting of the suspension units requires the use of two units, one at each side of the snowmobile, so as to insure against uneven loadings; thus, increasing the cost of the assembly.
It has been proposed, therefore, to provide a suspension system that is positioned within the area circumscribed by the drive belt. When the suspension system is so located, however, it is extremely difficult to insure the desired degree of suspension travel without interference with the components. Furthermore, in order to permit such internal mounting of the suspension unit, it has been proposed to use torsional, mousetrap type of springs. This type of spring has several disadvantages in that is has a high degree of hysteresis and, furthermore, may severely limit suspension travel.
The problems in locating a suspension arrangement for the drive belt of a snowmobile are particularly acute in connection with the suspension of the forwardmost portion of the drive belt. It is at this area where the space is of the minimum. Nevertheless, it is desirable to provide a suspension system for the forwardmost portion of the drive belt which cooperates with the rearwardmost suspension to avoid any significant change in the angles of the portion of the drive belt which engages the ground. Previously proposed suspension systems for the forwardmost portion of the drive belt have made it difficult to locate a conventional type of shock absorber in this area and still achieve the desired suspension characteristics. In addition, the previous suspension systems have dictated the use of such torsional mousetrap type springs as previously described. As noted, these arrangements provide a harsh ride and high hysteresis.
It is, therefore, a principal object of this invention to provide an improved, compact suspension unit for a vehicle such as a snowmobile.
It is another object of the invention to provide a compact snowmobile suspension unit which may be positioned within the driving track and which yet affords a high degree of suspension travel with adequate control throughout the range of travel.
It is yet a further object of this invention to provide an improved suspension system for the forward portion of the driving track of a snowmobile or the like.